High density disk drives (HDDs) utilize a magnetic storage medium shaped as a disk and an I/O head that reads data from and writes to the magnetic disk. The drive spins the magnetic disk rapidly, currently 5,400 RPM and 7,200 RPM drives are widely used. The I/O head moves radially across the disk to reach any desired location on the disk for reading and writing data. In response to an I/O request, the drive has to spin the magnetic storage medium up to speed and also move the I/O head to the correct reading location, which imposes spinning disk and head move (seek) time latency into the I/O response. Computer users are demanding improved I/O performance of the non-volatile storage component of their personal computing devices. This has led to the adoption of solid-state non-volatile storage that eliminates the data access delays common to HDDs introduced by rotational latency of the spinning disk and the recording head move (seek) time required to access the customer or operating system requested data.
The solid-state storage approach described above presents a drawback, however, because the solid state storage is relatively expensive, requires additional circuit board space, and adds a significant component to the cost of the system. There is, therefore, a continuing need for techniques to improve HDD I/O performance. More particularly, there is a need for HDD systems that do not rely on expensive solid state memory to improve the I/O performance of the system.